The present invention relates to electrical coupling assemblies, and more particularly, to electrical coupling assemblies sufficiently rugged to be used in vehicle magnetorheological shock absorbing systems.
Certain types of shocks, struts and other damping components used in vehicle shock absorbing systems have damping characteristics which can be varied to adjust the damping component to prevailing conditions. The damping characteristics may be varied to account for a number of factors, such as ambient temperature and the weight distribution, speed, and cornering status of the associated vehicle. Such dampers have generally contained adjustable valving, which introduces complexity and extra cost.
Recently, however, a new type of adjustable dampers are being introduced. Magnetorheological fluid dampers, also known as MR dampers, damp shock forces sustained by the vehicle by transmitting the forces to a piston which is pushed through a chamber filled with magnetorheological fluid. The piston is provided with an electric coil, and the flow of electric current in the coil may be controlled to vary the properties of the magnetorheological fluid pumped by the piston through an orifice in or adjacent the piston. In this manner the flow of magnetorheological fluid through the piston, and thereby the amount of damping, is controlled.
The piston that is pushed though the magnetorheological fluid is mounted onto the end of a rod, and electric current is provided to the coil in the piston from the end of the rod opposite the piston by means of an electric conductor in the rod. The conductor is electrically coupled to a connector, or coupling assembly, mounted on one end of the damper. The coupling assembly receives a plug that delivers power from the vehicle""s electrical system. In this manner, the coupling assembly connects the vehicle""s electrical system to the coil in the damper. However, existing coupling assemblies are difficult to assemble, lack robustness, and may not be fluid-tight to prevent water or other contaminants from contacting the wires or otherwise impairing the operation of the damper. And this is true even though the typical automotive strut is constructed with the piston at the bottom of the piston rod, with the opposite end of the rod projecting through a shock tower opening into the vehicle engine compartment. A coupling assembly for such a typical strut is thus at least somewhat protected from the outside environment.
But in order to relieve side loads on a damper piston rod, some struts are provided with an outer tube bearing a bracket adjacent its lower end for attachment to a vehicle wheel suspension assembly and which is closed at its lower end by a strut base. One end of the piston rod is fixed to the middle of the strut base, and the rod projects upward into an inner tube containing the piston and fluid. The top of the inner tube is fixed to the vehicle body, so that the rod and piston thus move axially together with the outer tube and wheel assembly in opposition to the inner tube and vehicle body. Side loads applied to the strut are received by bearing elements between the inner and outer tubes; and very little of these side loads are thus applied to the rod. A rod guide and seal assembly is provided to close the bottom of the inner tube, and the rod projects downward through the assembly.
An electrical conductor from a coil in the piston in such a strut exits the bottom of the rod; and the coupling assembly in such an xe2x80x9cupside downxe2x80x9d structure must therefore be placed at the bottom of the strut. In this position low in the vehicle suspension, out of the protective structure of the vehicle body, the coupling assembly is fully exposed to dirt, moisture and other contaminants, as well as extreme temperatures and physical shocks at the higher frequencies and amplitudes of the vehicle wheel rather than those of the vehicle body.
Accordingly, there is a need for an electrical coupling assembly which is durable, fluid tight, and easy to assemble. There is also a need for a MR strut that can resist side loads, has a rod with a relatively small diameter, and is controllable to adjust the strut to prevailing conditions.
It is an object of the present invention to provide an electrical coupling assembly which is sufficiently rugged and durable to be used in automotive applications; an electrical coupling assembly which is generally fluid-tight to protect the internal components of the coupling assembly and the associated mechanism; and an electrical coupling assembly which is relatively easy to fabricate and install. It is a further object of the invention to provide such an electrical coupling assembly in a controllable MR strut damper that has an outer tube to increase the capacity of the strut damper to resist side loads.
In one embodiment, the invention is an electrical coupling assembly for a damper, the coupling assembly including a base and a rod received through the base. The rod has a threaded connector end and a conductor extending through the rod from the connector end. The coupling assembly further includes a conductive nut threaded onto the connector end of the rod and a plug housing including a ground lead and a power lead, the power lead being electrically coupled to the conductor. The coupling assembly has a conductor engaging the plug housing and the nut, the conductor being electrically coupled to the ground lead.
In another embodiment of the invention, a magnetorheological damper for damping forces applied to a wheel suspension assembly of a vehicle includes an inner tube filled with magnetorheological fluid. The inner tube is connected to a frame of the vehicle, and a piston is located in the inner tube. A rod is connected to the piston and extends through the inner tube. The damper has an outer tube coaxial with the inner tube, the outer tube being connected to the rod and the wheel suspension assembly of the vehicle. The rod has a conductor extending along its length. The damper also includes an electrical coupling assembly connected to the rod and the conductor, the coupling assembly having a plug housing for receiving an external plug and for electrically coupling the external plug to the conductor. Other objects and advantages of the present invention will be apparent from the following description, the accompanying drawings and the appended claims.